(1) Field of the Invention
The present invention pertains to a heat exchanger cell for a furnace. In particular, the present invention pertains to a heat exchanger cell constructed of a pair of cell divisions joined by a seam extending around at least a portion of the circumference of the cell divisions, wherein the seam is formed with a crease extending along the seam and a plurality of indentations traversing the crease. The crease and indentations formed in the seam improve the ability of the seam to resist relative movement between the two heat exchanger cell divisions joined by the seam as the heat exchanger is repeatedly heated and cooled in the cyclic operations of a furnace employing the heat exchanger.
(2) Description of the Related Art
Heat exchanger cells of the type pertaining to the present invention are typically employed in numbers of two or more in forced air heating furnaces. In most cases, two or more of the heat exchanger cells are assembled side-by-side in the interior of a furnace. Air to be heated is blown between the heat exchanger cells and over their exterior surfaces by a blower. Each heat exchanger cell contains a burner that heats the exterior walls of the cell and, in turn, heats the air passed over the walls by the furnace blower.
A typical heat exchanger cell is constructed from a pair of cell division side walls. In many prior art heat exchanger cells, the cell divisions are joined along complementary rims of each division by the rim of one division being folded over and crimped around the rim of the other division.
In use, the heat exchanger cells are subjected to cyclic heating and cooling, resulting in the metal of the heat exchanger cell divisions alternately expanding and contracting in response to the alternating heating and cooling cycles of the furnace. The cyclic heating and cooling of the cells results in thermally induced stresses in the seams joining the cell divisions that can cause separation of the crimped folds of the seam.